1. Field of the Invention
The present invention relates to an ink-jet printhead and a method of manufacturing the same, and more particularly, to an ink-jet printhead having an improved heater structure and a method of manufacturing the ink-jet printhead.
2. Description of the Related Art
Ink-jet printheads generate bubbles in ink using a heat source and eject ink droplets using a force generated by the bubbles.
FIG. 1 schematically illustrates a structure of a conventional ink-jet printhead disclosed in U.S. Pat. No. 5,883,650. Referring to FIG. 1, an insulating layer 2 is formed on a substrate 1, and a heater 3 is provided above the insulating layer 2. A pair of conductors 4 contact both lower sides of the heater 3. A passivation layer 5 and a cavitation barrier 6 are sequentially stacked on the heater 3. A passage plate 7 providing (defining) an ink chamber is formed on the cavitation barrier 6, and a nozzle plate 8, on which a nozzle 9 is formed, is placed on the passage plate 7.
The conductors 4 are formed of aluminum and are patterned through wet or dry etching. However, the heater 3, the passivation layer 5, and the cavitation barrier 6 are formed through physical vapor deposition (PVD) such as sputtering. Thus, isotropic etching using wet etching is essential for the patterning of the conductors 4. According to the PVD, material layers are not deposited onto a step perpendicular to a deposition plane, and thus stoppage in forming the heater 5 occurs because of defects of the heater 5 occurring in deposition of the material layers on the step of the conductors 4. Thus, in order to prevent this stoppage, a slope should exist on the step of the conductors 4 under the heater 3 as shown in FIG. 1, so that a material layer is well deposited onto the substrate 1 during a PVD process. The slope is formed on the step of the conductors 4 by wet etching. Thus, in the ink-jet printhead having the above structure shown in FIG. 1, the patterning of the conductors 4 should be dependent on wet etching. However, wet etching causes a profile of an etched part to be uneven and rough. The processing of wet etching reduces uniformity and reliability of the conductors 4. Meanwhile, if the heater 3 is formed through the PVD, a deviation in a thickness of the heater 3 becomes very large. Due to the deviation, even in the ink-jet printhead having a plurality of nozzles, an electrical resistance between heaters corresponding to each of the nozzles becomes non-uniform.
Meanwhile, as shown in FIG. 1, the heater 3 is not completely covered by the passivation layer 5 and the cavitation barrier 6, but an edge of the heater 3 is exposed. This allows the edge of the heater 3 to contact ink, thereby greatly reducing a life span of the heater 3.